Matt Groening started out as an insecure cartoonist. ("I just never thought I could draw," he says.) His classic minimalist comic strip, "Life in Hell," which he started in the late '70s and is still syndicating today, eventually drew the admiring attention of James L. Brooks. This was most auspicious.

Brooks is an Academy-Award-winning writer and director ("Terms of Endearment," "Broadcast News") and a TV legend, too, having worked as a writer and producer on such iconic series as the "Mary Tyler Moore" show and "Taxi." Brooks suggested collaborating on an animation project, and Groening (rhymes with "raining") cooked up a concept: the highly quirky adventures of a blue-collar family that was loosely modeled on members of his own childhood household back in Portland, Oregon. These odd but lovable characters, the Simpsons, were launched in a series of shorts in 1987, on a TV variety series of the time, "The Tracey Ullman Show." In 1989, they were spun off into their own half-hour format on the then-young-and-hungry Fox network, to fairly instantaneous international acclaim. Today, "The Simpsons" is not only the longest-running animated show on American television, it's also the longest-running sitcom, period.

Now, after 18 years of TV acclaim (and a truckload of Emmys), Groening, Brooks and their closely-knit crew of writers, animators and voice actors have finally opened up the world of "The Simpsons" into a feature film. As fans of the series might expect, "The Simpsons Movie" is more of the same, only much more so. It's a very funny picture, and Groening and Brooks told us all about it during a recent swing through New York.

MTV: What was the genesis of this movie?

Matt Groening: A little newspaper article about pigs and pollution, and the problem of these gigantic pig farms. And then Homer falls in love with a pig, and the rest wrote itself.

MTV: There's sort of a mixed message about environmentalism in the movie, isn't there? On the one hand, Lisa is going around warning the townspeople that Lake Springfield is polluted — and they don't care. And on the other hand, the villain in the picture is the head of the Environmental Protection Agency.

James L. Brooks: We like to do the pro-and-con about whether to pollute the planet.

Groening: Pollution and the environment have been at the core of "The Simpsons" since the very beginning. Homer works at a nuclear power plant. He's not a good power plant worker — he causes a lot of meltdowns every week in the main titles. So we knew that the environment was going to be at the core of the movie, because it's at the core of the show.

MTV: There's also a long tradition of guest-star cameos on "The Simpsons," and there are a few in the movie, too. Were you able to just call up Green Day because they were fans and have them come in and do a song?

Brooks: Green Day is harder to get on the phone than anyone you can think of. I mean, we heard they wanted to do the movie. And they did want to do the movie. But it involved answering their phone.

MTV: It must have been liberating, expanding the TV show into a feature — you're able to have nudity, and kissing policemen. But you didn't push it too far.

Brooks: You just gave away the kissing policemen.

MTV: Sorry.

Groening: There were actually versions of the movie in which we did experiment with going in a coarser way [but it didn't work].

MTV: How did the longer time frame of making a movie affect the animation?

Groening: The animation is definitely much more ambitious in the movie than it was on TV. Finally we were able to do a "Simpsons" story where we took enough time to do it the way we wanted to. We were happy with the show, but we whip those things out; they're always under time constraints. With the movie, we took a great deal of time writing the script and really honing the animation.

And it was so much fun to be working with the "Simpsons" all-stars. The writers are people who used to run the show: Mike Scully; Al Jean, who still runs it; David Mirkin. And David Silverman, who directed the movie, was one of the three animators we had when we started out on the Tracey Ullman show.

MTV: You've created a lot of characters over the last 18 years.

Brooks: Our little writing room has a famous poster that has the whole population of Springfield. And we'd go over and say, We didn't get so-and-so in yet.

MTV: Did you have to cut characters for the movie?

Groening: Yeah, we were heartbroken — we had to give some characters the boot. Thank God they were cartoon characters and they couldn't whine. But we got a lot in.

Brooks: There are hundreds of speaking parts.

Groening: And we actually drew every character. I mean, every character you can imagine, they're in there someplace.

MTV: What do you think of the state of animation today generally? Are you a fan of the Pixar films like "The Incredibles"?

Groening: The Pixar stuff is a great use of that medium, of computer-generated images. But it's not "The Simpsons." I love the crude, hand-drawn line. It's not perfect, but you can see the humanity in it. CGI animation, when it's not done with the wit and style of those films, is cold and airless, and I don't think you can say that about our movie. It's definitely flawed and imperfect and crazy; but it's hand-drawn.

Brooks: One of our first trailers was "The Picture That Dares To Be Ugly."

Groening: I think there will always be a love of hand-drawn animation — in comic books too. Comic books aren't drawn by computer. Comic books are drawn by hand, and fans love the artist. David Silverman, you can see his hand in what's on the screen. You can see his gestures — it's the best kind of acting. Maybe some day computers will be able to match it, but that imperfection feels very classical in a way.

MTV: The "Simpsons" voice actors are also pretty important — to the show, and now in the movie.

Groening: The actors take it up to another level. I mean, the amount of improvisation by Dan Castellaneta changed the movie. Our favorite scene is with Dan, as Homer, trudging through the snow, talking to himself.

Groening: It's great when they do multiple characters in the course of a single scene. Then you have Harry Shearer playing Burns and Smithers and talking to himself back and forth. Or Dan Castellaneta as Homer and Grandpa having an argument. It's fantastic.

MTV: What are the writing sessions like for "The Simpsons"?

Brooks: Well, I think our youngest writer was eight when the series went on.

Groening: And these young writers have grown up watching the show. I can't remember what we did in season 11, you know? But they remember, and they go, "Oh, we already did that." "South Park" had an episode called "The Simpsons Already Did It," and it was about how they [would come up] with these ideas and there was a production assistant [who kept saying], " 'The Simpsons' already did it," and it drove them crazy. We have that same problem.

Brooks: All we can do is hate the person at the table that brings up that we did it already.

Groening: Considering that we're in a room for 10, 12 hours, it's surprisingly good-natured. There aren't many fist fights.

Brooks: You hear people laughing a lot. But that's because worrying doesn't make a noise.

MTV: Are there ever points where you feel, "We're slipping a little bit"?

Groening: It's an effort to continue to surprise the audience, especially when that's their expectation: "We're going to be surprised." That doesn't get any easier.

MTV: Why do you think the show has lasted so long?

Groening: At the very beginning, Jim said, "We've got to go for real emotion. We've got to make people forget that they're watching a cartoon ̬ they have to believe that these people are real." And so while I believe the jokes are pretty good, I think that's why this show has resonated with people for so long: because of the emotion.

MTV: Do you hear from the audience a lot? Do they e-mail you?

Brooks: I don't go online; he does. It's terrifying for me to go online and listen to everyone. There's nothing like an anonymous 14 year old messing with your head.

Groening: Everybody has an opinion. The diehard fans are also our biggest critics, and it's energizing to hear [what they think]. I love it.

MTV: Do you think "The Simpsons" could go on forever? Well, as long as human greed and stupidity exist?

Groening: Stupidity really helps. But yeah, there's no reason why it can't go on. Unless we're not having fun. And I think we're having more fun these days than we were before.